Question

The number of incorrect statement/s from the following is ____ .
A. The successive half lives of zero order reactions decreases with time.
B. A substance appearing as reactant in the chemical equation may not affect the rate of reaction.
C. Order and molecularity of a chemical reaction can be a fractional number.
D. The rate constant units of zero and second order reaction are mol L^–1s^–1 and mol^–1 Ls^–1 respectively.

Answer 1

Correct Answer: 1

Let's analyze each statement:

1. Statement A: The successive half-lives of zero-order reactions decrease with time. This statement is correct. For zero-order reactions, the half-life is directly proportional to the initial concentration, given by t_1/2 = [A]₀/2k. As the reaction proceeds, [A]₀ decreases, thus decreasing the half-life.
2. Statement B: A substance appearing as a reactant in the chemical equation may not affect the rate of reaction. This is correct. Some reactants might not appear in the rate law if they are present in large excess or do not affect the rate significantly.
3. Statement C: Order and molecularity of a chemical reaction can be a fractional number. This is incorrect. Order can indeed be fractional as it is determined experimentally. However, molecularity, being the number of molecules involved in an elementary step, must be an integer (often 1 or 2, rarely 3).
4. Statement D: The rate constant units of zero and second order reactions are mol L^–1s^–1 and mol^–1L s^–1 respectively. This is incorrect. For zero order, units are mol L^–1s^–1, but for second order, they should be L mol^–1s^–1.

Thus, there are two incorrect statements: C and D.

The number of incorrect statements is: 2.

The range given is 1 to 1. However, the correct computation results in 2 incorrect statements, suggesting a possible error in the provided range.